(a) Field of the Invention
The present invention relates to rechargeable lithium batteries.
(b) Description of the Related Art
In recent times, portable electronic equipment has reduced in size and weight in accordance with developments in electronics industries. As a result, these portable electronic devices are being increasingly used. Batteries having high energy density are needed as power sources for such portable electronic equipment, and rechargeable lithium batteries have been actively researched for this purpose.
Lithium-transition element oxides have been used as positive active materials for rechargeable lithium batteries, and crystalline or amorphous carbon-based active materials or carbon composites have been used as negative active materials. The active materials are coated on a current collector to an appropriate thickness and length. Alternatively, the active materials are made into a film. In either case, the active materials are used to fabricate electrodes, which are then wound or stacked with an insulating separator positioned between the electrodes to fabricate an electrode assembly. The electrode assembly is put into a can or other case and an electrolyte is injected therein to fabricate a rechargeable battery.
Recently, the demand for high-capacity and high voltage rechargeable lithium batteries has significantly increased, but rechargeable lithium batteries having sufficient performance and stability when used at high voltages of over 4.2V have not yet been developed.